Mahogany Homes

For me, there was 2 stages to construction training with mahogany homes. The first was oak plank contracts using the Varrock sawmill before Song of the Elves is completed, and the second was teak plank contracts after Song of the Elves using the Prifdinas sawmill.

Ring of the Elements earth altar teleport, but if you don't have that, teleporting to outside the Taverly POH and taking the balloon transport system to varrock is another way

Use the Ardougne cape to teleport to the Ardougne monastery, mine the coal and iron outside and use superheat to make steel bars

Book of the Dead/Kharedst's memoirs or teleport to Grand Exchange for the fairy ring.